Traditionally, cellular radio network systems were designed to run over frequencies exclusively licensed to specific mobile operators, and to gain this access right in a certain country or region carriers have often had to pay large amounts of money. This has been the case both 3G systems such as WCDMA, and indeed also for LTE.
Wi-Fi, on the other hand, i.e. Wireless LAN under IEEE standard 802.11, is a radio system that lacks the cellular design of e.g. LTE. In such a WLAN, several terminals may establish connection and exchange data with an access point base station without having to be registered to any carrier. In addition, any WLAN may be set up to make use of any part of an unlicensed radio band. Since different WLANs can overlap, and often do, there will be a risk for collisions between data packets sent at a common channel. This is handled by algorithms for collision avoidance, such as CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance), which are covered in the 802.11 specification. This system is, in a sense, more free. More specifically, it offers a possibility of very high bandwidth for any user.
Preparation is ongoing within 3GPP to start sending LTE signals over unlicensed frequencies, and trials have already been carried out. In the 5 GHz band, in which WLAN already may operate, there's more than 400 MHz of unlicensed spectrum available in most countries, and while no one will be able to use all 400 MHz at one time, an average subscriber who walks into range of an unlicensed LTE cell might get twice as much spectrum as in the licensed spectrum, according to certain estimates. The use of LTE on unlicensed bands has generally been considered for public places where there is coverage from licensed band LTE operation but where additional capacity would be beneficial, such as indoor cells or outdoor hot spots. Contrary to concern, the intention in the 3GPP work is not to define a standalone system that could be used in e.g. home environments, since there are existing solutions such as femto cell or Wi-Fi for that case. The proposed solutions are in fact designed to require co-existence of a licensed LTE connection. Unlicensed LTE is therefore named LAA (Licensed Assisted Access), an extra spectrum resource, especially on e.g. the 5 GHz frequency band, which can complement licensed bands. The technology and specifications developed will be a step towards mobile terminals using any kind of spectrum that's available, which is expected to continue in next-generation 5G networks.